We will first demonstrate that for the original DEF model (\(m_{\phi }=0\) ), neutron star mass-radius data can provide a lower bound for \(\beta \) : \(\beta \gtrsim -15\) . Our bounds are less stringent than the already existing ones obtained from binary star systems [1]}, [2]}, [3]}, but this demonstrates the effectiveness of mass-radius data in constraining deviations from GR as a proof of principle. Furthermore, our bounds are likely to improve as more data is obtained using electromagnetic [4]}, [5]}, [6]} and gravitational wave observations [7]}.
